As a method for protecting a superconducting coil (a method for preventing damage caused by a quench or the like), for example, there have been methods described in Patent Literatures 1 to 3. Patent Literature 1 describes a method in which a bridge circuit is connected to the both ends of a superconducting coil in parallel, and induced voltage noise etc. in an output of the bridge circuit is removed, thereby to improve accuracy in detecting a quench.
Patent Literature 2 describes a method in which, based on a detection signal from a quench detection circuit which detects a quench on the basis of an increase in voltage of a superconducting coil, electric current flowing through the superconducting coil is adjusted to prevent the quench of the superconducting coil.
Further, Patent Literature 3 describes a method in which a pickup coil is provided in the vicinity of a superconducting coil, and a quench is detected based on a voltage difference between a voltage generated in the superconducting coil and a voltage induced in the pickup coil.